Most of the nation’s recreational vehicle makers, whose factories are clustered in northern Indiana, crashed in the recession. But not Thor Industries Inc., owner of Four Winds, Airstream, Dutchmen and seven other units that sell nearly 50 RV brands in all, according to the Wall Street Journal.

After months of slashing jobs and closing factories, Thor is hiring again, and it expects to open two new factories before the end of the year. “The nadir in this industry is definitely behind us,” says Richard Riegel, chief operating officer of Thor, the nation’s biggest RV maker by sales.

Fierce, fast cost-cutting and a structure dominated by many small factories that were easy to open and close almost overnight helped Thor avoid the financial disasters that led to bankruptcy filings by its two big rivals. Those companies — Fleetwood Enterprises and Monaco Coach Corp. — had accounted for half of the industry’s preslump shipments.

Thor’s turnaround is helping to resuscitate the region, where unemployment reached 20%, making it a favorite destination of President Barack Obama as he pushed for economic-stimulus dollars. More than a dozen RV start-ups have emerged — most of them rising from the ruins of companies that went under — in northern Indiana, where about 70% of U.S. RVs are made and the RV Hall of Fame and Museum is housed.

Sales of RVs — ranging from simple, tow-behind trailers to land yachts outfitted with flat screens and full kitchens — peaked at more than 390,000 units in 2006, aided partly by a surge in hurricane-related sales. But they started to stall even before the recession because of $4-a-gallon gasoline. The industry’s problems quickly snowballed as consumer confidence evaporated and banks stopped lending for big-ticket purchases, including RVs.

Riegel recalls driving along Elkhart County’s back roads in the predawn cold last winter. “It’d be dark, it’d be nasty, and I’d see these fathers standing at the end of driveways with their kids waiting for the school bus,” he says. “I knew many of them were our workers” who were suddenly jobless.

This year, analysts predict sales will be 150,000, a 60% decline. But business is looking up as credit loosens and dealers restock inventory-drained showrooms. Shipments of RVs have increased in the last two months, and analysts now expect them to be up 25% next year.

That has helped Thor, as well as the new ventures that have emerged. Truck maker Navistar International  Corp. bought parts of Monaco, creating a new RV division. Portions of Fleetwood were bought by New York-based American Industrial Partners Capital Fund IV LP, a private-equity group.

Evergreen RV, in Middlebury, Ind., is a start-up that took over a factory formerly owned by Coachmen Industries Inc., which sold its RV business to Forest River Inc., a unit of Warren Buffett’s Berkshire Hathaway Inc., in late 2008. Evergreen, which touts an “eco-friendly” trailer made of recycled and light-weight materials, now has 60 workers.

Doug Lantz, Evergreen’s chief operating officer, says that when word of the factory reopening spread, job seekers lined up. “We had hundreds showing up and blocking the doors and the parking lot,” says  Lantz, who posted a sign on the road saying applications weren’t yet being accepted.

For Thor, which is based in Jackson Center, Ohio, hardship created opportunity. Ron Fenech, president of Thor’s Keystone division, which is based in Goshen, figures he gained at least 1.5 percentage points of market share as competitors faltered, giving his division more than 22% of the market.

“There were six months when the whole industry was in lockdown,” he says. But Keystone, which shed nearly 30% of its 3,000 workers in the last year, has hired back 400 since the summer.

The company, which makes towed trailers, is opening four production lines in its two new factories in Goshen. Trailers are generally less expensive than motorhomes, and sales in the segment have revived faster.

Thor’s secret is speed. The company is willing to expand or contract rapidly, lengthening or trimming shifts daily. Two factors have made that possible: the relatively small size of its factories and the production incentive offered to its workers. By contrast, its failed rivals took on debt, and some built sprawling, expensive plants.

In Goshen, Keystone operates a network of 16 factories, most of them no larger than 75,000 square feet, which is somewhat smaller than 1½ football fields.

The process uses a basic platform bought from an outside supplier that is pushed on a dolly to groups of skilled craftsmen. At different stations, plumbers, electricians and carpenters install pipes, wiring and cabinets.

Many employees are Amish craftsmen who ride bikes to work or are transported from nearby farms by hired drivers.

The workers are paid slightly more than minimum wage, but they still covet the jobs and the productivity bonus. It’s not unusual for RV workers to earn as much as $60,000 a year, Fenech says.